1. Silver nanoparticles enter the tree stem faster through leaves than through rootsClaudia Cocozza, Annalisa Perone, Cristiana Giordano, Maria Cristina Salvatici, Sara Pignattelli, Aida Raio, Marcus Schaub, Kruno Sever, John L. Innes, Roberto Tognetti, Paolo Cherubini, 2019, original scientific article Abstract: A major environmental pollution problem is the release into the atmosphere of particulate matter, including nanoparticles (NPs), which causes serious hazards to human and ecosystem health, particularly in urban areas. However, knowledge about the uptake, translocation and accumulation of NPs in plant tissues is almost completely lacking. The uptake of silver nanoparticles (Ag-NPs) and their transport and accumulation in the leaves, stems and roots of three different tree species, downy oak (Quercus pubescens Willd.), Scots pine (Pinus sylvestris L.) and black poplar (Populus nigra L.), were assessed. In the experiment, Ag- NPs were supplied separately to the leaves (via spraying, the foliar treatment) and roots (via watering, the root treatment) of the three species. Uptake, transport and accumulation of Ag were investigated through spectroscopy. The concentration of Ag in the stem was higher in the foliar than in the root treatment, and
in poplar more than in oak and pine. Foliar treatment with Ag-NPs reduced aboveground biomass and stem length in poplars, but not in oaks or pines. Species-specific signals of oxidative stress were observed; foliar treatment of oak caused the accumulation of H2O2 in leaves, and both foliar and root treatments of poplar led to increased O2− in leaves.
Ag-NPs affected leaf and root bacteria and fungi; in the case of leaves, foliar treatment reduced bacterial populations in
oak and poplar and fungi populations in pine, and in the case of roots, root treatment reduced bacteria and increased fungi in poplar. Species-specific mechanisms of interaction, transport, allocation and storage of NPs in trees were found.
We demonstrated definitively that NPs enter into the tree stem through leaves faster than through roots in all of the
investigated tree species.
Keywords: Ag-NPs, pathway of uptake, Pinus sylvestris L., Populus nigra L., Quercus pubescens Willd.
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2. Impact of high or low levels of phosphorus and high sodium in soils on productivity and stress tolerance of Arundo donax plantsClaudia Cocozza, Federico Brilli, Laura Miozzi, Sara Pignattelli, Silvia Rotunno, Cecilia Brunetti, Cristiana Giordano, Susanna Pollastri, Mauro Centritto, Gian Paolo Accotto, Roberto Tognetti, Francesco Loreto, 2019, original scientific article Abstract: The potential of Arundo donax to grow in degraded soils, characterized by excess of salinity (Na+), and phosphorus
deficiency (-P) or excess (+P) also coupled with salinity (+NaP), was investigated by combining in vivo
plant phenotyping, quantification of metabolites and ultrastructural imaging of leaves with a transcriptome-wide
screening. Photosynthesis and growth were impaired by+Na, -P and+NaP. While+Na caused stomatal
closure, enhanced biosynthesis of carotenoids, sucrose and isoprene and impaired anatomy of cell walls, +P
negatively affected starch production and isoprene emission, and damaged chloroplasts. Finally, +NaP largely
inhibited photosynthesis due to stomatal limitations, increased sugar content, induced/repressed a number of
genes 10 time higher with respect to+P and+Na, and caused appearance of numerous and large plastoglobules
and starch granules in chloroplasts. Our results show that A. donax is sensitive to unbalances of soil ion
content, despite activation of defensive mechanisms that enhance plant resilience, growth and biomass production
of A. donax under these conditions.
Keywords: Abiotic stress
Giant reed
Isoprene emission
Phosphorus
Salinity
Transcriptome
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